Induction Hardening Apparatus and Methods

ABSTRACT

An induction hardening apparatus and methods are provided. The induction hardening apparatus includes a feed line having first and second ends. A coil assembly is positioned between the first and second ends. The feed line includes a support arrangement for supporting two workpieces against one another and transferring the workpieces simultaneously through the coil assembly along a feed axis defined by the feed line.

FIELD OF THE INVENTION

This invention generally relates to heat treatment, and moreparticularly to induction hardening.

BACKGROUND OF THE INVENTION

Induction hardening is a non-contact heat treatment process whichutilizes the phenomena of inductive heating to harden all or a portionof a surface layer of a workpiece. During this process, the conductiveworkpiece is placed into a strong alternating magnetic current, therebycreating electrical currents on the surface of the workpiece. Theseelectrical currents flow predominantly into the surface layer of theworkpiece causing this layer to rapidly increase in temperature.

In the context of a steel workpiece, ideally the same is heated untilthe surface layer is at a temperature that is at or above thetransformation range temperature. Thereafter, the workpiece isimmediately quenched thereby forming a martensitic structure in thesurface layer that is harder than the base material. Generally, thehardened surface layer functions as a protective “skin” for theworkpiece, with reduced wear vulnerability. The aforementioned processis used in various applications, including tool tip hardening, pin andshaft hardening, blade edge hardening, etc.

There are generally two principal methods for induction edge hardening.The first is referred to as “single shot” hardening, wherein a workpieceis held statically in the alternating magnetic field so that the entirearea that will be heat treated is heated simultaneously. The secondmethod is referred to as “traverse” hardening, wherein the workpiecemoves through the alternating magnetic field progressively, so that thearea that will be heat treated is incrementally heated as it passesthrough the field.

In either case, both single shot and traverse edge hardening processesare known to produce substantial deformations in the workpiece. As aresult, a post-hardening straightening operation is required to removethe dimensional anomalies that result from these deformations to ensurethat the workpiece meets its required dimensional specifications.

Unfortunately, such a post-hardening straightening process is veryundesirable. From a cost perspective, this additional process increasesthe cost of manufacturing per part. From a lead time perspective, thisadditional process increases the overall processing time from order todelivery. Furthermore, the depth of the surface layer that is hardenedmust be deep enough to accommodate subsequent material removal duringstraightening. As such, the heat treated surface layer is often timesmuch deeper than necessary simply to ensure that a sufficient amount ofthe hardened surface layer will remain. To achieve this overshoot inhardened depth, higher frequency and power requirements are necessaryduring the induction edge hardening process to generate a sufficientamount of electrical current that will achieve the desired hardenedsurface layer depth.

Therefore, there is a need in the art for an edge hardening apparatusand method that will substantially reduce or entirely eliminate the needfor any post-hardening straightening operations. The invention providessuch an apparatus and method. These and other advantages of theinvention, as well as additional inventive features, will be apparentfrom the description of the invention provided herein.

BRIEF SUMMARY OF THE INVENTION

In one aspect, embodiments of the present provide a method for traverseinduction hardening. One embodiment of such a method may includealigning a pair of parts such that the parts are in a side-by-siderelationship with one another along their entire length such that onepart does not extend beyond the other part. The parts are aligned in apair such that an interior surface of one of the pair of parts is incontact with an interior surface of the other one of the pair of parts.The method further includes loading the aligned pair of parts into alinear track and feeding the aligned pair of parts along a linear trackalong a feed direction. The method further includes passing the alignedpair of parts through a coil assembly, such that at least a portion ofeach part of the pair of parts is simultaneously subjected to inductionheating. The method also includes simultaneously quenching each one ofthe pair of parts as they exit the coil assembly.

In certain embodiments, the method also includes aligning subsequentpairs of parts sequentially and in an abutted end-to-end relationshipsuch that each one of the aligned subsequent pairs of parts is alignedin an identical manner to each other one of the aligned subsequent pairsof parts.

In certain embodiments, the step of loading includes sequentiallyloading each one of the pairs of parts into the linear track. The stepof feeding includes sequentially and continuously feeding each one ofthe aligned pairs of parts along the feed direction. The step of passingincludes sequentially and continuously passing each one of the alignedpairs of parts through the coil assembly. The step of simultaneouslyquenching includes simultaneously quenching each one of each pair ofparts sequentially and continuously.

In certain embodiments, the step of loading includes positioning thealigned pair of parts into a channel of the linear track. The channel isdefined between two upstanding guides in an opposed space relation. Thestep of feeding the aligned pair of parts includes gripping the alignedpair of parts between at least one pair of rollers arranged adjacent tothe track. The step of feeding may also include gripping the alignedpair of parts between the at least one pair of rollers such that theinter surface of one part is held tightly against the interior surfaceof the other part. The step of feeding may also include gripping thealigned pair of parts successively by a plurality of pairs of rollersarranged sequentially adjacent to the track. The step of feeding mayalso include gripping the aligned pair of parts before it enters thecoil assembly, and after the aligned pair of parts exits the coilassembly.

In certain embodiments, the step of passing the aligned pair of partsthrough a coil assembly includes passing an uppermost edge of each oneof the pair of parts through the coil assembly simultaneously to edgeharden each one of the pair of parts.

The step of quenching may include passing the aligned pair of partsunder a quench head which directs a shower of coolant towards thealigned pair of parts. The step of quenching may also include separatingthe aligned pair of parts such that their respective interior surfacesare no longer in contact as the aligned pair of parts pass under thequench head. In certain embodiments, the method may also include a stepof passing the aligned pair of parts down a chute and into a quench bathafter passing the pair of parts under the quench head. In anotheraspect, embodiments of the present invention provide a method fortraverse induction hardening. An embodiment of a method according tothis aspect includes the steps of sequentially aligning pairs of partssuch that for each pair of parts, an interior surface of one part is incontact with an interior surface of the other part. The method alsoincludes sequentially loading each pair of aligned parts into a tracksuch that each one of the aligned pairs of parts are arranged in anabutted end-to-end relationship along the track to form a linear row ofaligned pairs of parts. The method also includes continuously feedingthe linear row of aligned pairs of parts through a coil assembly suchthat each pair of parts is sequentially subjected to induction heating.The method also includes separating the two parts of each pair of partsas they exit the coil assembly such that the interior surface of onepart of the pair of parts is no longer in contact with the other part ofthe pair of parts. The method also includes quenching each separatedpair of parts in a quenching station positioned adjacent the track suchthat coolant flows on the interior surface of both parts of theseparated pair of parts, as well as an exterior opposed surface of bothparts of the pair of parts.

In certain embodiments, the step of sequentially aligning includesaligning each pair of parts such that for each pair, the parts are in aside-by-side relationship and with one another along their entirelength.

In certain embodiments, the step of sequentially loading includesloading the pairs of parts into a channel of the track defined betweentwo upright opposed guides which extend generally perpendicular to abase surface.

In certain embodiments, the step of continuously feeding includesfeeding the linear row of pairs of parts through a plurality ofsequentially arranged rollers which are arranged in spaced-apart pairs.

In yet another aspect, embodiments of the present invention provide aninduction hardening apparatus. The apparatus according to this aspectincludes a track including a base surface and a pair of opposed guidesextending upwardly from the base surface to define a channel. A coilassembly for edge hardening parts via induction heating is alsoprovided. The coil assembly is positioned adjacent and above the track.The coil assembly is spaced from the track such that a portion of eachone of a pair of side-by-side parts may simultaneously pass through thecoil assembly. The apparatus also includes a feed arrangement configuredfor feeding a linear row of pairs of side-by-side parts along the trackin a feed direction through the coil assembly. The apparatus alsoincludes a quenching station downstream from the coil assembly relativeto the feed direction. The quenching station is positioned adjacent toand above the track and operable to quench the linear row of pairs ofside-by-side parts as they sequentially exit the coil assembly.

In certain embodiments, the opposed guides are spaced apart a firstdistance upstream of the coil assembly and spaced apart a seconddistance downstream of the coil assembly. The second distance is greaterthan the first distance. The feed arrangement may also include aplurality of rollers arranged sequentially in pairs such that the trackis interposed between the rollers of each pair of rollers. The spacingof the quenching station from an exit of the coil assembly may beadjustable to govern a delay of time from part heat-up to part quenchingat the quenching station.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a side view of one embodiment of an induction hardeningapparatus according to the teachings of the present invention;

FIG. 2 is a partial perspective view of a track of the inductionhardening apparatus of FIG. 1;

FIG. 3 is a side perspective view of a coil assembly of the inductionhardening apparatus of FIG. 1;

FIG. 4 is a partial perspective view of the coil assembly of FIG. 3;

FIG. 5 is a partial front cross section of parts exiting the coilassembly of FIG. 3; and

FIG. 6 is a partial perspective view of a quenching station of theinduction hardening apparatus of FIG. 1.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to FIG. 1, an exemplary embodiment of an induction hardeningapparatus 20 is illustrated. As will be explained in greater detailbelow, induction hardening apparatus 20 advantageously reduces orentirely eliminates the additional straightening step otherwise requiredby conventional transverse induction hardening apparatuses. Indeed,induction hardening apparatus 20 is operable to edge harden parts 22such that under typical dimensional specifications, no additionalstraightening step is required. Put differently, induction hardeningapparatus 20 substantially reduces or entirely eliminates partdeformations otherwise present after conventional induction edgehardening.

Induction hardening apparatus 20 feeds parts 22 along feed direction 24such that they pass through a coil assembly 26. While passing throughcoil assembly 26 parts 22 are edge hardened under the phenomena ofinduction edge hardening. Parts 22 are arranged in a side-by-siderelationship such that two parts 22 simultaneously pass through coilassembly 26. Further, pairs of parts 22 are arranged end-to-end asillustrated so that any given side-by-side pair of parts 22 begin andend the edge hardening process at the same time. Put differently, parts22 are arranged in identical pairs consisting of two side-by-side parts,with successive pairs arranged in an end-to-end relationship such that aleading edge of each one of a pair of parts 22 enters coil assembly 26at the same time, while a trailing edge of each of the parts 22 leavescoil assembly 26 at the same time.

To facilitate such an arrangement, induction hardening apparatus 20includes a track 34 for feeding pairs of parts 22 along feed direction24. Track 34 includes a pair of opposed guides 36 which support parts 22in a generally upright position. Track 34 is supported by a base stand38. A feed arrangement in the form of a plurality of feed rollers 46 aredisposed on either side of coil assembly 26 and are operable to feed theaforementioned pairs of parts 22 through coil assembly 26. Once throughcoil assembly 26, feed rollers 46 are also operable to feed pairs ofparts 22 along feed direction 24 such that parts 22 pass underneath aquench station 40 which exposes the heated parts 22 to a coolant quench.After passing through quench station 40, parts 22 fall along a chute 42and into a quench bath 44.

Induction hardening apparatus 20 is illustrated as schematicallyconnected to a power supply 48 for providing the required electricalpower for coil assembly 26, rollers 46, and other various sensors ofinduction hardening apparatus 20. It will be recognized that theparticular characteristics of power supply 48 will vary depending uponapplication, however one exemplary embodiment of a power supply 48 canbe an incoming electrical supply of 480 volt three phase electric powerat 60 Hz.

Induction hardening apparatus 20 is also illustrated as schematicallyconnected to a coolant supply 50. Coolant supply 50 is operable toprovide the quenching coolant to quench station 40, as well as replenishquench bath 44 as needed. Coolant supply 50 includes means forcirculating coolant throughout induction hardening apparatus 20. Thecoolant utilized may be organic or inorganic, and/or oil or water based.

Turning now to FIG. 2, a perspective view of track 34 is illustrated. Asillustrated, guides 36 depend upwardly from a base surface 50 of track34 and are generally perpendicular relative thereto. Guides 36 arearranged in an opposed space relationship such that a channel 52 isformed therebetween. Feed rollers 46 are disposed adjacent guides 36 andfunction in two respects.

First, feed rollers 46 feed adjacent parts 22 along feed direction 24(See FIG. 1) so that the parts 22 simultaneously pass through coilassembly 26 at an exemplary rate of about 30 ft./min. to about 60ft./min. Second, feed rollers 46 maintain tight contact between adjacentones of a pair of parts 22 so that good surface contact is maintained onthe interior sides of each part 22 of the pair of parts 22. Asillustrated, feed rollers 46 are disposed on either side of parts 22.Feed rollers 46 may be identical to one another, or alternatively, thefeed rollers 46 on one side of the pair of parts 22 may be of a greateror lesser hardness than the feed rollers 46 on the other side of thepair of parts 22. Further, belts, conveyors, etc. may be used in placeof or in addition to feed rollers 46 to feed the linear row of pairs ofparts 22 along feed direction 24. Yet further, feed rollers 46 on oneside of coil assembly 26 may be the same as, or a different size thanfeed rollers 46 on the other side of coil assembly 26. For example, feedrollers 46 upstream from coil assembly 26 may have a smaller diameterthan feed rollers 46 downstream from coil assembly 26.

Turning now to FIG. 3, quench station 40 is disposed a predetermineddistance W from the exit of coil assembly 26. The predetermined distanceW may be varied to allow for greater or lesser “soak” times, i.e. theamount of time that the parts remain at an elevated temperature prior torapid cooling at quench station 40. Furthermore, the size of channel 52increases to a distance D as illustrated adjacent quench station 40 toallow for a finished pair of parts 22 to separate so that coolant fromquench station 40 will pass on both the exterior and interior sides ofeach part 22 of the pair of parts 22. Such an arrangement insures thateach one of the pair of parts 22 is properly quenched and the desiredhardness is achieved on all intended surfaces.

Turning now to FIG. 4, as stated above, each one of a pair of parts 22enter coil assembly 26 at the same time. Parts 22 are fed by feedrollers 46 through a coil 54 of coil assembly 26. As illustrated, only aportion of parts 22 are exposed to coil 54 such that only a portion ofthe overall height of each upright part 22 is rapidly elevated intemperature by way of induction heating. In an exemplary embodiment, thetemperature of parts 22 is elevated from ambient to about 1700° F. Thoseskilled in the art will recognize that this configuration is an edgehardening application.

Turning now to FIG. 5, the portions of each part 22 which are elevatedin temperature are generally shown at regions 56. It will be recognizedthat regions 56 are simply a schematic representation that generallyillustrate the heated area of each part 22 under typical specificationsand operation, parts 22 are hardened to an exemplary case depth of about0.100″ to about 0.125″, and about 45 minimum RL. As indicatedpreviously, and illustrated throughout the various figures herein, parts22 are held tightly together in a side-by-side relationship asillustrated in FIG. 5. This side-by-side relationship allows for eachpart 22 to support the other part 22 such that deformations along thethickness of parts 22 are substantially reduced or entirely eliminated.Furthermore, because each pair of parts 22 is positioned end-to-endalong track 34 (See FIG. 1), the energy imparted to each part 22 as itpasses through coil assembly 26 may propagate to the other parts 22 insequential contact with the pair of parts 22 currently positioned incoil assembly 26. This alternative path of energy dissipation allows fora substantial reduction if not an elimination of part 22 deformation.

Turning now to FIG. 6, quench station 40 is shown in greater detail. Asindicated above, guides 36 in the region of quench station 40 are spacedapart at a distance D which is generally greater than the spacing ofguides 36 prior to encountering quench station 40. This allows parts 22to separate as they pass under quench station 40 to insure that coolantpasses over the interior and exterior sides of each part 22. Such aresult may be achieved by angling guides 36 in the region of quenchstation 40 as illustrated, or simply providing a separate set of guides36 which are spaced apart at distance D. Further, a dividing feature 60may be provided within channel 52 to aid in separating each pair ofparts 22 as they pass under quench station 40.

Having described the structural attributes of edge hardening apparatus20, a description will now be provided of the methods of operating thesame. Referring back to FIG. 1, a pair of similar parts 22 are arrangedsuch that their leading and trailing edges are adjacent one another. Thepair of parts 22 are then positioned approximate the left most roller 46in FIG. 1. Thereafter, other pairs of parts 22 are sequentially arrangedbehind the leading pair of parts 22. The induction hardening apparatus20 is then powered on allowing feed rollers 46 to pull the first pair ofparts 22 along feed direction 24. Simultaneously as this occurs, anoperator continues to feed pairs of parts 22 into track 34 at the leftmost end thereof by pushing the pair of parts into contact with thesequentially arranged pairs of parts 22 positioned on track 34. Thispushing by the operator insures that each of the pairs of parts 22maintain an end-to-end contact with one another as they pass throughcoil assembly 26.

Each pair of parts 22 then sequentially passes through coil assembly 26and is heated to a desired heat treating temperature. Upon exiting coilassembly 26 each pair of parts 22 is then exposed to a soak process,i.e. where the pairs of parts 22 continue to travel along feed direction24 in the ambient air after exiting coil assembly 26. These pairs ofparts 22 are at an elevated temperature until they reach quench station40 and are quenched. As the parts enter quench station 40, the parts areallowed to break the surface contact previously maintained between theinterior surfaces of each of the pair of parts 22 to allow coolant toflow over the exterior and interior surfaces of each part 22. Afterpassing through the quench station 40, the parts 22 travel along chute42 and are introduced to a quench bath 44. After resting in the quenchbath 44, parts 22 may be removed and are ready for storage and/orshipment.

As described herein, the induction hardening apparatus 20 advantageouslyprovides a system and method which substantially reduces or eliminatesentirely the need to conduct a post-hardening straightening operationwhich is otherwise required by conventional induction hardeningapparatuses. It has been observed that by the elimination of theaforementioned step part output per day has increased from a typical2,000 parts per day to 6,000 parts per day. As will be readilyappreciated, such a tripling of part output has led to significantreduction in part lead time. Further, the cost of manufacture of eachpart is substantially reduced given the elimination of theaforementioned post-hardening straightening step.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A method for traverse induction hardening, themethod comprising the steps of: aligning a pair of parts such that theparts are in a side-by-side relationship with one another along theirentire length such that one part does not extend beyond the other part,and such that an interior surface of one of the pair of parts is incontact with an interior surface of the other one of the pair of parts;loading the aligned pair of parts into a linear track; feeding thealigned pair of parts along the linear track along a feed direction;passing the aligned pair of parts through a coil assembly, such that atleast a portion of each part of the pair of parts is simultaneouslysubjected to induction heating; and simultaneously quenching each one ofthe pair of parts as they exit the coil assembly.
 2. The method of claim1, further comprising aligning subsequent pairs of parts sequentiallyand in an abutted end-to-end relationship such that each one of thealigned subsequent pairs of parts is aligned in an identical manner toeach other one of the aligned subsequent pairs of parts.
 3. The methodof claim 2, wherein the step of loading includes sequentially loadingeach one of the pairs of parts into the linear track, wherein the stepof feeding includes sequentially and continuously feeding each one ofthe aligned pairs of parts along the feed direction, wherein the step ofpassing includes sequentially and continuously passing each one of thealigned pairs of parts through the coil assembly, and wherein the stepof simultaneously quenching includes simultaneously quenching each oneof each pair of pair of parts sequentially and continuously.
 4. Themethod of claim 1, wherein the step of loading includes positioning thealigned pair of parts into a channel of the linear track, the channelbeing defined between two upstanding guides in an opposed spacedrelation.
 5. The method of claim 1, wherein the step of feeding thealigned pair of parts includes gripping the aligned pair of partsbetween at least one pair of rollers arranged adjacent to the track. 6.The method of claim 5, wherein the step of feeding includes gripping thealigned pair of parts between the at least one pair of rollers such thatthe interior surface of one part is held tightly against the interiorsurface of the other part.
 7. The method of claim 6, wherein the step offeeding includes gripping the aligned pair of parts successively by aplurality of pairs of rollers arranged sequentially adjacent the track.8. The method of claim 7, wherein the step of feeding includes grippingthe aligned pair of parts before it enters the coil assembly, and afterthe aligned pair of parts exits the coil assembly.
 9. The method ofclaim 1, wherein the step of passing the aligned pair of parts through acoil assembly includes passing an uppermost edge of each one of the pairof parts through the coil assembly simultaneously, to edge harden eachone of the pair of parts.
 10. The method of claim 1, wherein the step ofquenching includes passing the aligned pair of parts under a quench headwhich directs a shower of coolant towards the aligned pair of parts. 11.The method of claim 10, wherein the step of quenching includesseparating the aligned pair of parts such that their respective interiorsurfaces are no longer in contact as the aligned pair of parts passunder the quench head.
 12. The method of claim 11, further comprisingthe step of passing the aligned pair of parts down a chute and into aquench bath after passing the aligned pair of parts under the quenchhead.
 13. A method for traverse induction hardening, the methodcomprising the steps of: sequentially aligning pairs of parts such thatfor each pair of parts, an interior surface of one part is in contactwith an interior surface of the other part; sequentially loading eachpair of aligned parts into a track such that each one of the alignedpairs of parts are arranged in an abutted end to end relationship alongthe track such that a linear row of aligned pairs of parts is formed;continuously feeding the linear row of aligned pairs of parts through acoil assembly, such that each pair of parts is sequentially subjected toinduction heating; separating the two parts of each pair of parts asthey exit the coil assembly such that the interior surface of one partof the pair of parts is no longer in contact with the other part of thepair of parts; quenching each separated pair of parts in a quenchingstation positioned adjacent the track such that coolant flows on theinterior surface of both parts of the separated pair of parts, as wellas an exterior opposed surface of both parts of the pair of parts. 14.The method of claim 13 wherein the step of sequentially aligningincludes aligning each pair of parts such that for each pair, the partsare in a side-by-side relationship with one another along their entirelength.
 15. The method of claim 13 wherein the step of sequentiallyloading includes loading the pairs of parts into a channel of the trackdefined between two upright opposed guides which extend generallyperpendicular to a base surface.
 16. The method of claim 13, wherein thestep of continuously feeding includes feeding the linear row of pairs ofparts through a plurality of sequentially arranged rollers which arearranged in spaced apart pairs.
 17. An induction hardening apparatus,the apparatus comprising: a track including a base surface and a pair ofopposed guides extending upwardly from the base surface to define achannel; a coil assembly for edge hardening parts via induction heating,the coil assembly positioned adjacent and above the track, the coilassembly spaced from the track such that a portion of each one of a pairof side-by-side parts may simultaneously pass through the coil assembly;a feed arrangement configured for feeding a linear row of pairs ofside-by-side parts along the track in a feed direction through the coilassembly; and a quenching station downstream from the coil assemblyrelative to the feed direction, the quenching station positionedadjacent to and above the track and operable to quench the linear row ofpairs of side-by-side parts as they sequentially exit the coil assembly.18. The apparatus of claim 17, wherein the opposed guides are spacedapart a first distance upstream of the coil assembly and spaced apart asecond distance downstream of the coil assembly, the second distancegreater than the first distance.
 19. The apparatus of claim 18, whereinthe feed arrangement includes a plurality of rollers arrangedsequentially in pairs such that the track is interposed between therollers of each pair of rollers.
 20. The apparatus of claim 19, whereinthe spacing of the quenching station from an exit of the coil assemblyis adjustable to govern a delay of time from part heat up to partquenching at the quenching station.